The present invention relates to a prestressing strand joint structure for use in a prestressed concrete construction method and also relates to a method of constructing the prestressing strand joint structure.
A conventional prestressing strand joint is accommodated in a steel coupler sheath as it is and buried in placed concrete. The inside of the coupler sheath is filled with cement grout after the prestressing strands have been anchored under tension.
Accordingly, after the concrete has hardened, the inside of the coupler sheath cannot be seen at all. Therefore, it is impossible to check the filling condition in the coupler sheath and to repair a possible defect unless the concrete is chipped.
Accordingly, the present invention solves the above-described problem by providing a prestressing strand joint structure and a construction method therefor characterized in that a joint between prestressing strands is covered with a coupler sheath, particularly a transparent coupler sheath, and a resin filling material is filled in the coupler sheath.
The features of the present invention are as follows. A joint between prestressing strands, particularly pregrouted cables, is covered with a transparent coupler sheath so that a resin filling material can be filled in the coupler sheath and the filling condition can be visually checked from the outside of the coupler sheath. If there is a defect in filling, the resin filling material is injected excessively from an injection opening so that excess resin filling material is discharged from a discharge opening, thereby allowing the coupler sheath to be satisfactorily filled with the resin filling material. Alternatively, the resin filling material may be partially injected, or the coupler may be disassembled immediately to correct the operation.
That is, the present invention provides a prestressing steel stranded wire joint structure and a construction method therefor arranged as follows.
(1) A prestressing steel stranded wire joint structure includes a transparent coupler sheath for covering a joint made between prestressing steel stranded wires with a prestressing steel stranded wire coupler, the transparent coupler sheath having a resin filling material injection opening and discharge opening provided in a tube wall thereof, and a slow curing resin filling material filled in the transparent coupler sheath.
(2) In a prestressing steel stranded wire joint structure as stated in the above paragraph (1), the resin filling material is a slow curing epoxy resin.
(3) In a prestressing steel stranded wire joint structure as stated in the above paragraph (1) or (2), the resin filling material is a greasy resin having low resistance to deformation when it is in an uncured state.
(4) In a prestressing steel stranded wire joint structure as stated in the above paragraph (2) or (3), the filling material having a slow curing epoxy resin as a principal component contains a latent curing agent.
(5) In a prestressing steel stranded wire joint structure as stated in the above paragraph (2) or (3), the slow curing epoxy resin filling material contains a curing accelerator.
(6) In a prestressing steel stranded wire joint structure as stated in any of the above paragraphs (1) to (5), the prestressing steel stranded wires are pregrouted cables.
(7) A method of constructing a prestressing steel stranded wire joint, includes the steps of covering a joint between prestressing steel stranded wires with a transparent coupler sheath having a slow curing resin filling material injection opening and discharge opening provided in a tube wall thereof, the joint being made with a prestressing steel stranded wire coupler; injecting a resin filling material into the transparent coupler sheath from the injection opening to fill the transparent coupler sheath with the resin filling material; and embedding the whole outer peripheral portion of the prestressing steel stranded wire joint, including the coupler sheath, with placed concrete.
(8) A method of constructing a prestressing steel stranded wire joint, includes the steps of covering a joint between prestressing steel stranded wires with a transparent coupler sheath having a slow curing resin filling material injection opening and discharge opening provided in a tube wall thereof, the joint being made with a prestressing steel stranded wire coupler; injecting a resin filling material into the transparent coupler sheath from the injection opening to fill the transparent coupler sheath with the resin filling material; embedding the whole outer peripheral portion of the prestressing steel stranded wire joint, including the coupler sheath, with placed concrete; and applying tension to the prestressing steel stranded wires after the concrete has hardened and before the resin filling material cures.
(9) In a method of constructing a prestressing steel stranded wire joint as stated in the above paragraph (7) or (8), the resin filling material is a slow curing epoxy resin.
(10) In a method of constructing a prestressing steel stranded wire joint as stated in the above paragraph (9), the filling material having a slow curing epoxy resin as a principal component contains a latent curing agent.
(11) In a method of constructing a prestressing steel stranded wire joint as stated in the above paragraph (9) or (10), the slow curing epoxy resin filling material contains a curing accelerator.
(12) In a method of constructing a prestressing steel stranded wire joint as stated in any of the above paragraphs (7) to (11), the prestressing steel stranded wires are pregrouted cables.